This invention relates to the use, in food products, of high stearic soybean blended with other oils or fats.
Most natural fats and oils contain only cis double bonds, but partial hydrogenation results in the formation of trans fatty acid substituents, which have been recently shown to raise low density lipoprotein serum cholesterol levels and to lower high density lipoprotein serum cholesterol levels in adults fed fats having these acids (Mensink, R. P., and Katan, M. B., New Eng. Jour. Med. 323: 439-445 (1990)).
Since many food products contain partially hydrogenated fats (especially products having a structural fat component comprising a plastic fat or hardstock), various research efforts have been directed to the development of edible fats that mimic the physical and organoleptic properties of partially hydrogenated fats but have diminished or zero trans acid contents. For example, interesterified fat products have been prepared using fully hydrogenated hardstocks (U.S. Pat. No. 3,617,308 to Graffelman), including those having no trans isomers (List, G. R., et al., J. Amer. Oil Chem. Soc. 54: 408-413 (1977)). Low trans fat products have also been prepared by fractionating an interesterified mixture of liquid and completely hydrogenated oil (U.S. Pat. No. 4,425,371 to Stratmann, et al.).
Another approach to low trans products makes use of directed interesterification to prepare fats from liquid oil without the aid of hydrogenation. For example, directed interesterification of sunflower and safflower oils at low temperatures in an aprotic solvent (U.S. Pat. No. 3,859,447 to Sreenivasan) or of corn oil with temperature cycling in the absence of solvent (U.S. Pat. No. 4,419,291 to Lathauwer, et al.) has been disclosed. However, using most oils, the technique yields a plastic product having limited functionality.
In addition to the isomerism of the unsaturated substituents of dietary fats, the saturated substituents also appear to modulate plasma cholesterol concentrations. Recent evidence shows that some fats, notably those high in lauric acid (12:0), myristic acid (14:0), or palmitic acid (16:0) apparently increase plasma cholesterol concentrations, while fats high in stearic acid do not (Bonanome, A., and Grundy, S. M., New Eng. Jour. Med. 318: 1244-1248 (1988)).
A number of publications report the preparation of fats enriched with stearic acid. Fats may be fractionated to yield plastic and hardstock fractions having special characteristics, such as palm stearins (U.S. Pat. No. 4,366,181 to Dijkshoorn and Huizinga) or high stearin butterfat (U.S. Pat. No. 4,438,149 to Verhagen and Bodor). Butterfat has been hardened and then fractionated to obtain fractions suitable for use in margarine (see U.S. Pat. No. 4,479,976 to Lansbergen and Kemps and U.S. Pat. No. 4,504,503 to Biernoth and Merk). Natural fat blends that were substantially free of hydrogenated and interesterified fats have also been disclosed for producing margarines (see, for example, U.S. Pat. No. 4,366,181 to Dijkshoorn, et al.).